In rural road construction, the use of which of the following is preferred for ensuring environmental sustainability or to reduce carbon footprint? [2020]

In rural road construction, the use of which of the following is preferred for ensuring environmental sustainability or to reduce carbon footprint?

Copper slag, a by-product of the copper smelting process, offers a prime example of waste being converted into wealth and contributing to environmental sustainability. Generated during the extraction of copper from sulphide ore, copper slag primarily consists of iron silicates. India alone produces approximately 22.17 million tons of copper slag annually from companies like Birla Copper, Sterlite Copper, and Hindustan Copper, while globally, 400 million tons are generated each year.
Contrary to common misconceptions, copper slag is not classified as hazardous waste. Regulatory bodies such as the US Environmental Protection Agency (US EPA) have declared it non-hazardous, after extensive studies. In India, the Bureau of Indian Standards (BIS) and the Indian Roads Congress (IRC) have approved the use of copper slag in various applications, including road construction, cement blending, and concrete production. In construction, copper slag improves the strength of concrete when used as a substitute for sand and gravel. Its inert nature, stability, and poor leachability ensure minimal environmental impact, even in large-scale usage. The material is also known to reduce the carbon footprint in construction.

This method uses asphalt emulsions that don’t require heating, significantly reducing energy consumption during production and construction compared to traditional hot mix asphalt. Additionally, cold mix asphalt can often incorporate recycled materials, further lowering its environmental impact.

Geotextiles are permeable fabrics that, when combined with soil, serve functions such as separation, filtration, reinforcement, protection, and drainage. Commonly made from synthetic polymers or natural fibres, they improve soil stability and drainage in road construction. By reducing the dependence on natural aggregates, geotextiles help extend the lifespan of roads, decreasing the need for frequent repairs and maintenance, and thus contributing to sustainability.

As mentioned earlier, this method requires significant energy for heating the asphalt, leading to higher carbon emissions compared to cold mix.

While commonly used in construction, its production is energy-intensive and contributes significantly to carbon emissions.